1. Field of the Invention
The present invention relates to piezoelectric components such as a surface acoustic wave (SAW) device used in a SAW duplexer or SAW filter, or a piezoelectric thin film filter, that are used for example in mobile communication equipment such as mobile telephones, and a manufacturing method thereof, and relates in particular to a chip-size packaged piezoelectric component which enables probe testing at the wafer (piezoelectric substrate) level, and a manufacturing method thereof.
2. Description of Related Art
In a piezoelectric component (SAW device) to be installed in a mobile phone or the like, the formation of a predetermined hollow section around the comb-shaped electrodes (IDT electrodes) thereof is required.
Conventionally, to reduce the size of a SAW device, a SAW element chip is flip-chip bonded (face-down bonded) to a wired substrate using gold (Au) bumps or solder bumps, and the entire SAW element chip is subjected to resin encapsulation by resin or the like to configure a flat type-face SAW device (refer to Japanese Unexamined Patent Publication No. 2004-147220).
In addition, to reduce the size and height of a SAW device, a microminiaturized chip size packaged SAW device is proposed in which a predetermined hollow section is formed around a comb-shaped electrode section (IDT electrode section), and while maintaining this gap, the entire integrated piezoelectric substrate (wafer) on the comb-shaped electrode side, is sealed by resin, external connection electrodes are formed, and then the wafer is divided into individual SAW devices by dicing along predetermined markings (refer to Japanese Unexamined Patent Publication No. 2006-246112).
However, with the piezoelectric components and manufacturing methods thereof described in the related art above, because piezoelectric elements are formed upon a two-dimensional flat surface (principal surface) of the piezoelectric substrate, implementing both an inspection step during the manufacturing process of the piezoelectric element, and an electroplating step carried out in a later step, is extremely difficult, and with plating methods other than electroplating (for example, electroless plating), ensuring high quality and lowering costs for the SAW device is difficult.
In other words, when a probe test of piezoelectric elements is performed on a piezoelectric substrate (wafer), and then plating of predetermined locations thereon is performed, because the terminal electrodes which form the electrode posts will not all have the same electric potential, either electroless plating is performed, or a sheet layer is formed upon the piezoelectric substrate and then protected with a resist before performing electroplating, after which the resist and sheet layer must be removed by etching.
However, after the wiring electrodes are formed on the piezoelectric substrate, once more sealing with resin to form a hollow section surrounded by outer wall sections and a ceiling section is difficult.
Furthermore, when plating is performed directly onto the terminal electrodes, an electroless plating method is needed, but in electroless plating the plating formation speed is extremely slow (in electroless Cu plating, the plating formation speed is slow at approximately 2 μm/hour), and the photosensitive resist already coated onto the piezoelectric substrate has to be immersed long-term in a strong alkaline solution, and consequently a problem occurs in that the resin used for sealing becomes damaged.